Comment by myself248

Replying to myself here. I just found myself shopping for a washer and dryer, and indeed, ran across one that takes manufacturer-branded detergent cartridges and offers to order more, right in the app, when they run low.

It can use third-party detergent by manually adding it at the start of the cycle, but adding some _during_ the cycle (which ultimately uses less) is only supported if using their cartridge.

I wish I was making this up.